Lubricant coat forming apparatus

ABSTRACT

The present invention provides a lubricant coat forming apparatus for forming a dry coat of water dry type lubricant on the surface of each of cold plastic working materials. The apparatus includes a heating unit for heating the cold plastic working materials to a predetermined temperature, a lubricant applicator for applying the lubricant on the surfaces of the cold plastic working materials heated at the heating unit, and a drying unit for drying the lubricant applied on the surfaces of the cold plastic working materials by applying cooling air stream to them. The cooling air stream has a temperature lower than that of the cold plastic working materials heated by the heating unit.

BACKGROUND OF THE INVENTION

1. Background of the Invention

The present invention relates to an apparatus for forming a dry coat ofthe lubricant for cold forging on cold plastic working materials (e.g.,rod, tubular, plate and other shaped members, sintered materials, etc.,made of steel, titanium, titanium alloy, copper, copper alloy,aluminium, or aluminium alloy), which are cold forged by using apressing machine.

2. Description of the Prior Art

Recently employed process applied to cold forging of the cold plasticworking materials includes is forming thereon a dry coat of thelubricant for cold forging. Specifically, the process includes heatingthe cold plastic working materials to a predetermined temperature,applying water dry type lubricant on the heated materials, and applyingheated air stream of a temperature higher than that of the cold plasticworking materials, thereby drying the lubricant applied on thematerials.

The above process, which includes drying the cold plastic workingmaterials heated to a predetermined temperature by the application ofthe heated air stream having a temperature higher than that of thematerial, poses a problem that the cold plastic working materials areheated to an excessively high temperature. This excessively hightemperature of the materials may shorten the life of a metal mold in thepressing machine when the materials for cold plastic working of such anexcessively high temperature is fed to the pressing machine. To avoidthis problem, a material cooling time is needed to lower the temperatureof the cold plastic working materials prior to being fed to the pressingmachine.

To heat the cold plastic working materials to a predeterminedtemperature in a conventional manner, a heating chamber is disposed in aconveying line of the cold plastic working materials, through which thecold plastic working materials successively pass, so that they areheated under a high temperature atmosphere within the heating chamber.This conventional heating arrangement inherently requires a lengthenedheating chamber extending along the conveying path so as to heat thecold plastic working materials during the conveyance of the cold plasticmaterials at a usual transfer speed. However, when the heating chamberis to be installed in a limited space, it may not have a sufficientlength, with the result that the transfer speed needs to be lowered toallow the cold plastic materials to stay within the heating chamber fora prolonged period of time.

In either way, a prolonged period of time is needed for forminglubricant dry coat, which is disadvantageous in the fact that such alower coat-forming speed cannot match the operation speed of thepressing machine.

Therefore, it is an object of the present invention to provide alubricant coat forming apparatus that is capable of forming a dry coatat a sufficient speed to match the operational speed of the pressingmachine.

SUMMARY OF THE INVENTION

Extensive efforts have been devoted by the present inventors to achievethe above object. These efforts have led to the finding of the fact thatthe temperature of the air stream for drying the coat affects on the drytime. Upon such a fact, the present inventors have obtained theknowledge that cooling air stream would be suitable for shortening acoat drying time rather than using a hot air stream, and hence achievedthe present invention.

Specifically, according to one aspect of the present invention, there isprovided a lubricant coat forming apparatus for forming a dry coat ofwater dry type lubricant on the surface of each of cold plastic workingmaterials. The apparatus includes a heating unit for heating the coldplastic working materials to a predetermined temperature, a lubricantapplicator for applying the lubricant on the surfaces of the coldplastic working materials heated at the heating unit, and a drying unitfor drying the lubricant applied on the surfaces of the cold plasticworking materials by applying cooling air stream to the cold plasticworking materials. The cooling air stream has a temperature lower thanthat of the cold plastic working materials heated by the heating unit.

By “heating the cold plastic working materials to a predeterminedtemperature”, it is meant that the cold plastic working materials areheated to a temperature higher than the atmospheric temperature (e.g.,not less than 60° C.). By “the air stream has a temperature lower thanthat of the cold plastic working materials heated by the heating unit”,it is meant that the air stream has a temperature lower than that thetemperature (predetermined temperature) of the cold plastic workingmaterials themselves, which have been heated by the heating unit. Forexample, when the cold plastic working materials are heated to about 60°C. at the heating unit, it is preferable to set the temperature of thecooling air at lower than about 60° C., more particularly in the rangebetween 25 to 45° C.

According to another aspect of the present invention, there is provideda lubricant coat forming apparatus for forming a dry coat of water drytype lubricant on the surface of each of cold plastic working materials.The apparatus includes a heating unit for heating the cold plasticworking materials to a predetermined temperature, a lubricant applicatorfor applying the lubricant on the surfaces of the cold plastic workingmaterials heated at the heating unit, a drying unit for drying thelubricant applied on the surfaces of the cold plastic working materials.The heating unit includes a plurality of storage chambers disposed atintervals for respectively storing the cold plastic working materials, athrow-in port through which the cold plastic materials are thrown intothe plurality of storage chambers, and a discharging port through whichthe cold plastic working materials are discharged from the plurality ofstorage chambers. The plurality of storage chambers are adapted totravel along a circular path starting from the throw-in port andreturning thereto via the discharging port. The heating unit furtherincludes a heated air application means for applying heated air streamto the cold plastic working materials stored in the plurality of storagechambers, thereby heating the cold plastic working materials to apredetermined temperature.

With the above arrangement, the cold plastic working materials aresuccessively thrown into the plurality of storage chambers through thethrow-in port. The storage chambers with the cold plastic workingmaterials therein travel along the circular path. During the travel, theheated air stream is directly applied to the cold plastic workingmaterials to heat them to a predetermined temperature, and the coldplastic working materials are then successively discharged towards thelubricant applicator.

According to still another aspect of the present invention, there isprovided a lubricant coat forming apparatus for forming a dry coat ofwater dry type lubricant on the surface of each of cold plastic workingmaterials. The apparatus includes a heating unit for heating the coldplastic working materials to a predetermined temperature, a lubricantapplicator for applying the lubricant on the surfaces of the coldplastic working materials heated at the heating unit, and a drying unitfor drying the lubricant applied on the surfaces of the cold plasticworking materials. The heating unit includes a plurality of storagechambers disposed at intervals for respectively storing the cold plasticworking materials, a throw-in port through which the cold plasticmaterials are thrown into the plurality of storage chambers, and adischarging port through which the cold plastic working materials aredischarged from the plurality of storage chambers. The plurality ofstorage chambers are adapted to travel along a circular path startingfrom the throw-in port and returning thereto via the discharging port.The heating unit further includes a means for immersing the cold plasticworking materials stored in the plurality of storage chambers in a hotbath, thereby heating the cold plastic working materials to apredetermined temperature.

According to another aspect of the present invention, there is provideda lubricant coat forming apparatus for forming a dry coat of water drytype lubricant on the surface of each of cold plastic working materials.The apparatus includes a heating unit for heating the cold plasticworking materials to a predetermined temperature, a lubricant applicatorfor applying the lubricant on the surfaces of the cold plastic workingmaterials heated by said heating unit, and a drying unit for drying thelubricant applied on the surfaces of the cold plastic working materials.The heating unit includes a plurality of storage chambers disposed atintervals for respectively storing the cold plastic working materialstherein, a throw-in port through which the cold plastic materials arerespectively thrown into the plurality of storage chambers, and adischarging port through which the cold plastic working materials aredischarged from said plurality of storage chambers. The plurality ofstorage chambers are adapted to travel along a circular path startingfrom the throw-in port and returning thereto via the discharging port.The heating unit further includes a means for immersing the cold plasticworking materials stored in the plurality of storage chambers in hotwater, thereby heating the cold plastic working materials to apredetermined temperature.

With the above arrangement, the cold plastic working materials aresuccessively thrown into the plurality of storage chambers through thethrow-in port. The storage chambers with the cold plastic workingmaterials therein travel along the circular path. During the travel, thecold plastic working materials are immersed in the hot water to beheated to a predetermined temperature, and the heated cold plasticworking materials are then successively discharged towards the lubricantapplicator.

BRIEF DESCRIPTION OF THE DRAWINGS

The above, and other objects, features and advantages of the presentinvention will become apparent from the detailed description thereof inconjunction with the accompanying drawings wherein.

FIG. 1 is a schematic plan view of a lubricant coat forming apparatusaccording to one embodiment of the present invention.

FIG. 2 is a front view partially broken away of a portion of a heatingunit of the lubricant coat forming apparatus.

FIG. 3 is a side view of the heating unit.

FIG. 4 is a front view of an essential portion of the heating unit.

FIG. 5 is a cross section of the essential portion of the heating unit.

FIG. 6 is a schematic perspective view of a drying unit of the lubricantcoat forming apparatus.

FIG. 7 is a schematic cross section of the drying unit of the lubricantcoat forming apparatus according to another embodiment of the presentinvention.

FIG. 8 is a front view of a heating unit of a lubricant coat formingapparatus according to still another embodiment of the presentinvention.

FIG. 9 is a side view of the heating unit of FIG. 8.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

With reference to the attached drawings, the description will be madefor one embodiment of the lubricant coat forming apparatus with anarrangement that the water dry type lubricant for cold forging isapplied on the surfaces of cold plastic working materials 1 to be coldforged, and the applied lubricant is subsequently dried to form a drycoat of the lubricant on the surface of each cold plastic workingmaterial 1.

The lubricant coat forming apparatus of the present invention can beapplied to the cold plastic working materials of various shapes.However, for the illustrative purpose, this embodiment will be describedby taking for example the case that rod shaped cold plastic workingmaterials each having a stepped configuration with a head portion lahaving a larger diameter and a tail portion having a smaller diameterare processed.

FIG. 1 is a schematic plan view of the lubricant coat forming apparatusaccording to this embodiment, which is illustrated as being located in aconveying line adapted to feed the cold plastic working materials to apressing machine therethrough. Aligned in sequence from the upstream tothe downstream of the lubricant coat forming apparatus are a heatingunit 2 as a heating means for heating the cold plastic working materials1 to a predetermined temperature, an applicator 3 as a lubricantapplication means for applying lubricant to the surfaces of the coldplastic working materials 1 heated at the heating unit 2, and a dryingunit 4 as a drying means for drying the lubricant applied on thesurfaces of the cold plastic working materials at the applicator 3. Theconveying line for conveying the cold plastic working materials 2includes a conveyor belt 5, which hangs the cold plastic workingmaterials 1 with their axes generally vertically orienting during theconveyance, and horizontally orienting just before the cold plasticworking materials 1 are fed into the heating unit 2 and just after theyare discharged therefrom, so that the head portions 1 a having a largerdiameter face oppositely with respect to the heating unit 2 or tailportions having a smaller diameter face the heating unit 2. Thedescription will hereinbelow be made subsequently for the respectivesteps.

First Embodiment

As illustrated in FIG. 2, the heating unit 2 includes a rotating drum 7having a cylindrical body with storage chambers 6 for respectivelystoring the cold plastic working materials 1 therein, a fixed covermember 8 covering the rotating drum 7 to constitute a substantiallysealed heating chamber.

The storage chambers 6 of the rotating drum 7 each extend parallel tothe axis of the rotating drum 7 and are open to the outside of therotating drum 7 through both end surfaces of the rotating drum 7. Thestorage chambers 6 are disposed around the circumferential periphery ofthe rotating drum 7 at intervals. In this embodiment, 34 storagechambers are disposed at a constant pitch of substantially elevendegrees on the same circle.

The rotating drum 7 includes a substantially horizontally extendingrotating shaft 9 adapted to be driven by a motor 13, two circular plates10 respectively fixed to the front and rear sides of the rotating shaft9, and a plurality of hollowed cylindrical members 11 extending betweenboth circular plates 10. The circular plates 10 each define roundedholes around the circumferential periphery at intervals to securelyreceive the cylindrical members 11, thereby respectively forming thestorage chambers 6 within the cylindrical members 11. The rotating shaft9 extends through the cover member 8 to have both ends thereof supportedby side walls 12 of the cover member 8, and one of said both endsprojecting away from the cover member 8 and operatively connected to themotor 13 via a driving chain 14, thereby transmitting a driving force ofthe motor to the rotating shaft 9. The motor 13 is controlled tointermittently rotate with an intermittent pitch matching with the pitchof the storage chambers 6.

The cover member 8 has a shape adapted to the outer contour of therotating drum 7, and includes a circumferential wall 15 covering thecircumferential periphery of the rotating drum 7, and front and rearside walls 12 a and 12 b respectively covering both sides of therotating drum 7 oppositely disposed with respect to the axis of therotating drum 7. Defined in the front side wall 12 a are a materialthrow-in port 16 (material throw-in member) through which the coldplastic working materials 1 fed by the conveyor belt 5 are thrown in anda material discharging port 17 (material discharging member) throughwhich the cold plastic working materials 1 are discharged onto theconveyor belt 5. Both ports have a rounded hole configuration and arealigned along the circular path of the storage chambers 6. The anglesbetween the throw-in port 16 and the discharging port 17 are integralmultiples of the spacing pitch of the storage chambers 6. The rear sidewall 12 b defines therein a rounded hole (not shown) whose positioncorresponds to the discharging port 17, so that the storage chambers 6each are aligned with the rounded hole and the discharging port 17 ateach stop during the intermittent operation of the rotating drum 7.Disposed rearwards to the rear side wall 12 is a pusher 18 movable intoand away from the storage chambers 6 through the rounded hole to pushthe cold plastic working materials 1 out of the storage chambers 6through the discharging port 17 of the front side of the rotating drum7, thereby feeding them onto the conveyor belt 5 located forwards to therotating drum 7. When two lines of the conveyor belt 5 are arranged, anadditional throw-in port 16 a is preferably formed for a different line,as illustrated in FIG. 2.

The heating unit 2 is designed to heat the cold plastic workingmaterials 1 to a temperature higher than surrounding temperature byapplying heated air stream to them stored in the storage chambers 6.Specifically, the front side wall 12 a of the cover member 8 definestherein a heated air sending port in the form of a slit 19 forintroducing the heated air stream therethrough, as illustrated in brokenlines in FIG. 2. The slit 19 extends in the circumferential direction ofthe front side wall 12 a within a predetermined angular range betweenthe throw-in port 16 and the discharging port 17, and is provided on thefront side thereof with a heated air stream supplying duct 20 having asealed inner space therein, which is positioned in such a manner as tocover the slit 19. On the other hand, the rear side wall 12 b definestherein a heated air discharging port in the form of a slit 21 fordischarging the heated air stream therethrough, whose positioncorresponds to the slit 19, and is provided on the rear side thereofwith a heated air stream discharging duct 22 having a sealed inner space(see FIG. 5).

The slit 19 has a width narrower than the diameter of the storagechambers 6, so that highly pressurized air stream can pass through thestorage chambers 6, which are moved with their axes orthogonal to thelengthwise direction of the slit 19. The slit 21 has a width wider thanthat of the slit 19 and substantially equal to the diameter of thestorage chambers 6.

As illustrated in FIG. 1, the ducts 20 and 22 are communicated with eachother via an air circulating passage 23, which is provided with a fan 24as an air sending means for sending the air to the duct 20 for the aircirculation between the ducts, and a heater 25 as an air heating meanswhich heats the air to maintain the temperature of the heated air streamfed through the slit 19 at a predetermined level.

With the above arrangement, the heated air stream sent by the fan 24 isreheated to a predetermined temperature by the heater 25 controlled by acontrol means, then sent to the duct 20 through the air circulatingpassage 23, and then introduced into the inside of the cover member 8through the slit 19. Since there exists little clearance between thecorresponding side wall 12 and circular plate 10, the heated air streamsent through the slit 19 is mostly introduced into those of the storagechambers 6 travelling along the slit 19 to be in communication with theair circulating passage 23 via the slit 19, passes through therespective storage chambers 6, and then is drawn into the duct 22through the opposite slit 21. During the heated air stream passesthrough the storage chambers 6, the temperature drop occurs in thatstream due to the heat transmission to the cold plastic workingmaterials 1. The heater 25 reheats the air stream to constantly send theheated air stream to the storage chambers 6 at a predeterminedtemperature. The cold plastic working materials 1 are heated to, forexample, about 60° C. by the heating unit 2.

Now, the description will be made for the applicator 3 that applieslubricant to the surfaces of the cold plastic working materials 1 heatedto a predetermined temperature at the heating unit 2.

As illustrated in FIG. 1, the applicator 3 is disposed between theheating unit 2 and the drying unit 4, and includes a lubricant reservoir26 for storage liquidized lubricant and a holding member (not shown).The holding member is constructed in such a manner as to hold the coldplastic working materials 1 conveyed by the conveyor belt 5 with theiraxes vertically oriented, and reciprocate in the vertical direction,allowing the cold plastic working materials 1 to be successivelyimmersed in the lubricant. The lubricant in the reservoir 26 has atemperature equal to the temperature of the cold plastic workingmaterials 1 to retain the heated temperature of the cold plastic workingmaterials 1. For example, the lubricant is set at about 60° C. Means forapplying the lubricant may be take various forms, such as a nozzle fordischarging pressurized lubricant therethrough.

The description will also be made for the drying unit 4 for drying thelubricant with reference to FIG. 6. The drying unit 4 has an elongatedbox shape with a longitudinal axis extending along the direction ofconveyance, and includes a drying chamber 27 with outlet and inlet ports28 defined therein open to the upstream and downstream sides of theconveying path, and an endless conveyor chain 29 extending in a straightline parallel to the conveying path for receiving the cold plasticworking materials 1 from the applicator 3 and conveying the same throughthe drying chamber 27 in a straight line. In this embodiment, twoendless chains 29 are arranged parallel to one another with theconveying path therebetween, allowing the cold plastic working materials1 to hang from the parallel endless chains 29 during the conveyance.

The drying chamber 27 includes a highly pressurized air dischargingmember 30 disposed at the upstream side for blowing away the stagnantlubricant on the cold plastic working materials 1 conveyed by theparallel endless chains 29 with highly pressurized air, and an airblower 31 disposed at the downstream side of the highly pressurized airdischarging member 30 for applying air stream towards the cold plasticworking materials 1 from below, thereby drying the lubricant. Providedabove the drying chamber 27 are exhaust fans 32 for exhausting the airto the above.

The highly pressurized air discharging member 30 includes nozzles 33respectively located upper, lower and lateral sides with respect to theparallel endless chains 29, so that the pressurized air can be appliedto substantially the entire surface of the cold plastic workingmaterials 1 through these nozzles. The air blower 31 is formed by an airblowing tube 34 disposed along the conveying path and under the parallelendless chain 29, and has nozzles 35 in the upper side of the tube 34 atintervals along the lengthwise direction. The air blowing tube 34 iscommunicated with an air sending means (not shown) to feed a dry outsideair of, for example, about 30° C., thereby applying to the cold plasticworking materials 1 the air stream cooler than the cold plastic workingmaterials 1.

In the lubricant forming apparatus according to this embodiment, thetemperature and conveying time for each step for the dry lubricantformation are set in such a manner as to allow the cold plastic workingmaterials 1 to have a temperature between 50 and 60° C., on theassumption that the room temperature surrounding the pressing machine is40° C. That is, the temperature and conveying time for each step are setto allow the cold plastic working materials 1 to have a temperaturehigher, or preferably 10° C. higher than the room temperaturesurrounding the pressing machine.

The water dry type lubricant may be that sold under the tradenameFINELUVE™ 750H by Nihon Parkerizing Co., Ltd. However, it is notnecessary to limit the water dry type lubricant to this product. Variouslubricants can be used.

The description will now be made for the operational steps for theformation of the lubricant dry coat on the surface of the cold plasticworking materials 1.

The cold plastic working materials 1 are first conveyed to the heatingunit 2 by the conveyor belt 5, and then rotated 90 degrees along theconveying path just before the heating unit 2 to have the tail portionsfacing the heating unit 2. Thereby, the cold plastic working materials 1are conveyed into the storage chambers 6 through the throw-in port 16,while maintaining its horizontally held position. After one of the coldplastic working materials 1 is placed in a corresponding storagechambers 6, the rotating drum 7 rotates in the clockwise direction asviewed from the conveyor belt 5 by a predetermined angle, and stops, sothat the rotating drum intermittently rotates to successively introducethe storage chambers 6 to the throw-in port 16. In this embodiment, thestorage chambers 16 travel along the circular path around the rotationaxis of the rotating drum 7. Since the rotating drum rotatessynchronously with the conveyor belt 5, the cold plastic workingmaterials 1 fed by the conveyor belt 5 are successively placed into thestorage chambers 6.

When the storage chambers 6 with the cold plastic working materials 1therein reach the slit 19 through the rotation of the rotating drum 7,the heated air stream introduced through the slit 19 pass through thestorage chambers 6, during which the heated air stream can directly beapplied to the cold plastic working materials 1, as illustrated in FIG.5. The application of the heated air stream to each cold plastic workingmaterial 1 is continued up to the time when a corresponding storagechamber 6 passes through the slit forming region. During the applicationof the heated air stream, the cold plastic working materials are heatedto a predetermined temperature (e.g., about 60° C.). The heated coldplastic working materials 1 are then successively pushed out of thestorage chambers 6 towards the front side of the rotating drum 7 and fedonto the conveyor belt 5 by the pusher 18 when the corresponding storagechambers 6 are drawn to the discharging port 17, where the pusher 18repeatedly moves into and out of the storage chambers 6 insynchronization with the rotating drum 7. After the cold plastic workingmaterials 1 are unloaded from the storage chambers 6, the empty storagechambers 6 travel back to the throw-in port 16 for receiving new coldplastic working materials 1.

According to the above heating step, the heating unit 2 employs arotating arrangement, which is advantageous in a limited installingspace as compared with a rectilinear arrangement. In addition, thedirect application of the heated air stream to the cold plastic workingmaterials 1 is advantageous in the fact that the heating time forheating them to a predetermined temperature can be shortened as comparedwith the heating operation carried out in a hot ambient environment. Asa further advantage, the above arrangement allows the heated air streamto flow straight through the storage chambers 6 in the axial directionof the rotating drum 7, and the cold plastic working materials 1 to beplaced in such air stream, so that the heat efficiency is improved.Thus, the cold plastic working materials 1 can securely be heated in ashort period of time, unlike a simple application of the heated airstream.

Since the heating unit 2 of this embodiment has an arrangement that theslit 19 continuously extends along the circular path (in thecircumferential direction), and the heated air stream supplying duct 20covers the slit 19 throughout the entire length of the slit 19, thecontinuous stream of the heated air can be formed in the circumferentialdirection of the rotating drum 7, unlike the arrangement where theheating is carried out only at a single point on the way to thedischarging port 17. The cold plastic working materials 1 thus passthrough such a continuous air stream in the orthogonal direction to thestream direction, so that the heated air stream can be applied to thecold plastic working materials 1 both during the rotating and stoppingstates of the rotating drum 7. This continuous application of the heatedair stream can achieve more efficient heating of the cold plasticworking materials 1, and limit variation in heated temperature of eachcold plastic working material. In addition, the head portions having alarger diameter of the cold plastic working materials, which are hard tobe heated, face the slit 19 can be easily heated in the same manner asthe tail portions.

The most of the heated air stream introduce through the slit 19 passesthrough the respective storage chambers 6 and into the heated air streamdischarging duct 22, thereby limiting the heat loss. Therefore, theheating operation by the heater 25 can be economically performed, andthe temperature control or the control of the heater 25 can easily beachieved. A plurality of small holes can be defined in each hollowedcylindrical member 11. However, it is preferable to form no small holesin order to increase the amount of the heated air stream passing throughthe storage chambers 6, and hence limit the heat loss.

The cold plastic working materials 1 subjected to the heating processand fed on the conveyor belt 5 are then turned 90 degrees with respectto the conveying path from the horizontal orientation to the verticalorientation, successively conveyed towards the applicator 3, and fed onthe holding member (not shown) of the applicator 3. The holding memberis lowered to immerse the cold plastic working materials 1 in thelubricant, thereby applying the lubricant on their surfaces. The holdingmember is then moved upwards to the conveying level of the conveyorbelt, and feed the cold plastic working materials 1 on the endlessconveyor chain 29. In this lubricant application process, thetemperature of the lubricant is equal to the heated cold plastic workingmaterials 1, so that they can be fed to the drying unit 4 withoutlowering the temperature of the cold plastic working materials 1.

However, it is possible to set the lubricant at ambient temperature orthe like. In that case, the heating temperature of the heating unit 2 ispreferably set to be slightly higher than that in the above mentionedoperation.

The conveyor chain 29 of the drying unit 4 then transfers the coldplastic working materials 1 into the drying chamber 27, in which thestagnant lubricant is blown away from the cold plastic working materials1 through the application of the pressurized air discharged through thenozzles 33 to the surfaces of the cold plastic working materials 1,thereby obtaining a uniform thickness of the lubricant coat. After that,the cooling air discharged from the air blowing tube 34 is applied tothe cold plastic working materials 1 from below to dry the lubricant.When the cold plastic working materials 1 are moved out of the dryingchamber 27, the lubricant dry coats are formed on their surfaces. Sincethe lubricant is dried through the application of the cooling airstream, it is possible to prevent the excessive heating of the coldplastic working materials 1, and simultaneously achieve the shorteningof the lubricant drying time. In addition, the exhaustion of the air tothe outside of the drying chamber 27 through the exhaust fans 32 reducesmoisture in the drying chamber 27.

As described above, the lubricant coat forming apparatus according tothis embodiment can shorten the heating time by using the heating unit2, and also shorten the drying time by using the drying unit 4, with theresult that the total time for forming the dry coat can be remarkablyshortened. Thus, such a shortened tact time for feeding the cold plasticworking materials 1 to the pressing machine can sufficiently cope with ahigh-speed pressing machine.

The most proper thickness of the dry coat depends on the finished shapeof metallic materials, finished surface roughness, and the like.However, the dry coat may have a thickness in the range between 1 to 50μm, and more preferably 5 to 40 μm. When the dry coat is excessivelythin, it may burn. Contrarily, an excessively thicker dry coat may causeclogging in the die of the pressing machine, which may in turn causedefect in shape of the resulting products, and/or such a thicker drycoat may have the dry coat which cannot be drawn into the die or ontoprocessing surface, and excluded therefrom, resulting in substantialloss of the water dry lubricant.

The effectiveness in drying the lubricant was evaluated by applying aheated air stream, and a cooling air stream respectively to the coldplastic working materials. The testing results are as follows:

When the cold plastic working material of 50° C. with a lubricant coatthickness of 100 μm is dried with a heated air stream of 125° C., ittook 125 seconds for the cold plastic working material to have a driedlubricant thickness of 30 μm, or reduce the contained water by 70%. Onthe contrary, when the cold plastic working material of 63° C. havingthe same lubricant coat thickness is dried with a cooling air stream of27° C., the necessary time for obtaining the same dried thickness anddried condition was 48 seconds, which is less than a half of the abovetime period. The drying by the application of a heated air stream alsoincreased the temperature of the cold plastic working material 1 to 70°C. after the drying (in 125 seconds). On the contrary, the drying by theapplication of a cooling air stream decreased the temperature of thecold plastic working material 1 to 52° C. In the testing, the thicknessof the lubricant dry coat was measured by using a coat thicknessmeasuring instrument, and the thickness of the lubricant wet coat wascalculated from the cubic volume of the lubricant and the lubricantapplied surface area. In this testing, the lubricant was that sold underthe tradename of FINELUVE™ 750H by Nihon Parkerizing Co., Ltd., but theother lubricants also produced the same effect.

In the aforesaid description, the drying unit 4 has an arrangement whichallows the cooling air to be applied to the cold plastic workingmaterials 1 from below. However, it is possible to employ thearrangement where air feeding tubes 37 are respectively disposed in thelateral side of the conveying path of the cold plastic working materials1 substantially throughout the length of the drying chamber 27 todischarge the cooling air in the horizontal direction via a number ofsmall holes 36 defined in the laterally inwardly facing sides of the airfeeding tubes 37, as illustrated in FIG. 7.

The heating means for heating the cold plastic working materials 1 to apredetermined temperature may take various forms in addition to theheated air application arrangement. For example, the cold plasticworking materials 1 may be immersed in a hot bath. In this case, thecold plastic working materials 1 stored in the storage chambers 6 of therotating drum 7 may be successively immersed in the hot bath as they arerotated by the rotating drum 7. An example of different heat applicationarrangement will be described hereinbelow. Corresponding or identicalparts to those of the first embodiment have been given the samereference characters to omit the detailed description thereof.

Second Embodiment

As illustrated in FIGS. 8 and 9, the heating unit 2 includes therotating drum 7 having a cylindrical body with the storage chambers 6for respectively storing the cold plastic working materials 1 therein,and a hot bath 36 that holds hot water kept at a predeterminedtemperature and is disposed to allow a part of the rotating drum 7 to beimmersed in the hot water. The hot bath 36 is an alternative to thecover member 8 of the first embodiment covering the rotating drum 7 toconstitute a substantially sealed heating chamber.

The storage chambers 6 of the rotating drum 7 each extend parallel tothe axis of the rotating drum 7 and are open to the outside of therotating drum 7 through both end surfaces of the rotating drum 7. Thestorage chambers 6 are disposed around the circumferential periphery ofthe rotating drum 7 at intervals. In this embodiment, thirty six storagechambers are disposed at a constant pitch of substantially ten degreeson the same circle.

The rotating drum 7 includes the substantially horizontally extendingrotating shaft 9 adapted to be driven by the motor 13, the two circularplates 10 respectively fixed to the front and rear sides of the rotatingshaft 9, and the plurality of hollowed cylindrical members 11 extendingbetween both circular plates 10. The circular plates 10 each definerounded holes around the circumferential periphery at intervals tosecurely receive the cylindrical members 11, thereby respectivelyforming the storage chambers 6 within the cylindrical members 11. Therotating shaft 9 extends through the circular plates 10 to be supportedthereon, in which one end of the rotating shaft 9 projects away from thecover member 8 and is operatively connected to the motor 13 via thedriving chain 14, thereby transmitting a driving force of the motor tothe rotating shaft 9. The motor 13 is controlled to intermittentlyrotate with an intermittent pitch matching with the pitch of the storagechambers 6.

The hot bath 36 is disposed to accommodate substantially a lower half ofthe rotating drum 7, and holds hot water of such an amount as not toimmerse the rotating shaft 9 therein. Specifically, in this embodiment,the hot water is held within the hot bath to immerse fifteen cylindricalmembers 11 therein. The hot water is kept at a temperature between 60and 70° C. by sheath heaters 37 as heating means disposed at properpositions in the hot bath 36.

A pipe 38 extends into the hot bath 36 to feed hot or cold water fromthe outside. The hot bath 36 has a bottom surface slightly tilting tohave a lower side with a drain pipe 39 connected thereto. An auxiliarybath 40 is connected to a part of the hot bath 36 to collect the hotwater from the hot bath 36 and purify the collected hot water via adischarging pipe 41 connected to the auxiliary bath 40.

Since the heating unit 2 of this embodiment is not provided with thecover member 8 unlikely to the first embodiment, the cold plasticworking materials 1 are directly placed into the cylindrical members 11,and then directly discharged onto the conveyor belt 5 after subjected tothe hot bath treatment. Therefore, the material throw-in port 16 islocated so as to correspond in position to a cylindrical member 11located just before the point at which the cylindrical members 11 areimmersed in the hot water, or a cylindrical member 11 located at thethird position from the surface of the hot water in the reversedirection of the rotating drum 7, while the material discharging port 17is located so as to correspond in position to a cylindrical member 11which has been moved out of the hot water, or a cylindrical member 11located at the uppermost position of the rotating drum 7. When two linesof the conveyor belt 5 are arranged, a cylindrical member 11 at adifferent position is preferably selected to form an additional throw-inport 16 or discharging port 17 for an additional line of the conveyorbelt 5.

Disposed rearwards to one of the circular plates 10 is the pushermovable into and away from the storage chambers 6 through the roundedhole to push the cold plastic working materials 1 out of the storagechambers 6 through the discharging port 17, thereby feeding them ontothe conveyor belt 5 located forwards to the rotating drum 7.

According to the thus arranged heating unit 2, the cold plastic workingmaterials 1 thrown into the storage chambers 6 through the throw-in port16 are intermittently rotated at a predetermined pitch (about 2sec./pitch), so that they are immersed within the hot bath 36 for apredetermined period of time (about 2 sec.×16 pitches=about 32 sec.).During the immersing, the cold plastic working materials 1 are heated toa temperature slightly lower than the hot water. For example, the coldplastic working materials 1 are heated to a temperature between 55 and65° C., when the hot water has a temperature between 60 and 70° C. Itwill be understood that there are not any substantial differences inarrangement for throw-in and discharging of the cold plastic workingmaterials 1 between the first and second embodiments.

The above heating arrangement produces desirable effects. Specifically,the heating unit 2 of a rotational type contributes to a smaller sizedhot bath 36, and a smaller sized installing space. The smaller sized hotbath 36 desirably has a reduced amount of the hot water. The heatingarrangement with the hot bath also produces an effect of washing awaydusts or any undesirable matters from the cold plastic working materials1, and hence forming a dry coat of a more uniform thickness.

The hot water held within the hot bath 36 is set to have a temperaturearound a temperature desirable for the cold plastic working materialssubjected to the heating treatment, so that, even if the time periodrequired for the hot bath immersing treatment, or the time periodrequired for the cold plastic working materials 1 to be immersed in thehot water is varied within a certain range, the cold plastic materials 1after the hot bath immersing treatment are unlikely to have atemperature greatly varied. Accordingly, the heating arrangement of thisembodiment is advantageous in the fact that the temperature control ofthe cold plastic working materials 1 in the heat treatment can easily beaccomplished.

Although the hot water of 60 to 70° C. hardly causes an undesirableeffect, a cover member is preferably placed on the hot bath 36 of theheating unit 2 to avoid the diffusion of the evaporated water from thehot bath 36. Although the cylindrical members 11 having the open ends,through which the hot water is introduced into the storage chambers 6,may not pose a problem, a plurality of small holes are preferably formedin each cylindrical member 11 to accomplish a smooth communication ofthe hot water between the inside and outside of each storage chamber 6by means of punching treatment or the like. Moreover, the heating unit 2may have the rotating shaft 9 immersed in the hot water, as long as theliquid tightness for the rotating shaft 9 of the rotating drum 7 can beassured.

As is apparent from the above description, the heating arrangement withthe hot bath is also advantageous in the fact that the heating time forheating the cold plastic working materials to a predeterminedtemperature can be shortened as compared with the heating operationcarried out in a hot ambient environment, resulting in a shortenedperiod of time for forming lubricant dry coat.

This specification is by no means intended to restrict the presentinvention to the preferred embodiments set forth therein. Variousmodifications to the lubricant coat forming apparatus, as describedherein, may be made by those skilled in the art without departing fromthe spirit and scope of the present invention as defined in the appendedclaims.

What is claimed is:
 1. A lubricant coat forming apparatus for forming adry coat of water dry lubricant on the surface of each cold plasticworking materials, which comprises: a heating unit for heating the coldplastic working materials to a predetermined temperature; a lubricantapplicator for applying the lubricant on the surfaces of the plasticworking materials heated by said heating unit; a drying unit for dryingthe lubricant applied on the surfaces of the plastic working materials;and said heating unit including a plurality of storage chambers disposedat intervals for respectively storing the plastic working materialstherein, a throw-in port through which the plastic materials arerespectively thrown into said plurality of storage chamber, and adischarging port through which the plastic working materials aredischarged from said plurality of storage chambers, said plurality ofstorage chambers adapted to travel along a circular path starting fromsaid throw-in port and returning thereto via said discharging port, andsaid heating unit further including a means for immersing the plasticworking mateials in the plurality of storage chambers in hot water,thereby heating the plastic working materials to a predeterminedtemperature.
 2. A lubricant coat forming apparatus according to claim 1,wherein said drying unit is adapted to apply cooling air stream to theplastic working materials to the dry the lubricant applied on thesurfaces of the plastic working materials, said cooling air streamhaving a temperature lower than that of the plastic working materialsheated by said heating unit.